See this word history:
The word canvas came into Middle English, via Old Northern French
canevas, from the Latin name for hemp, cannabis: hemp is the raw
material traditionally used in making canvas, and is also the source
of cannabis itself. The noun canvas (earlier spelled with a double -s)
is also linked with the verb canvass, which originally meant ‘toss in
a canvas sheet’ (a practice carried out both in fun and as a
punishment); canvass then came to mean ‘assault, attack’ or
‘criticize’, and later ‘scrutinize in order to reject invalid votes’,
from which developed the modern sense, ‘solicit votes’.